1. Technical Field
This invention relates generally to a process for manufacturing artificial firelogs and, more particularly, to an extrusion process for manufacturing artificial firelogs having a flat rear surface. Specifically, the invention relates to a method for manufacturing artificial firelogs in which a component mixture is compressed through an extrusion die having a dividing blade traversing the die. The dividing blade, mandrel, and extrusion die cooperate to form a pair of firelogs having rounded front surfaces, a flat rear surface, and a channel down the rear surface.
2. Background Information
Various types of artificial firelogs have been developed and are well understood in the relevant art. These artificial firelogs are typically used in domestic fireplaces to produce aesthetically pleasing fires. The principal and by far most common use of the logs is in a domestic fireplace to provide an attractive fire closely simulating a wood fire and that is at least as safe, if not safer, than a wood fire.
These artificial firelogs are generally formed of particulate combustible materials that are compressed into a desirable shape. Most of these firelogs are formed of a particulate cellulosic material such as sawdust, although other combustible materials such as coal particles may be used. The particulate materials are combined with binder materials such as molasses, various waste oils or pitches, waxes, and other such combustible binders that maintain the shape of the firelog. Firelogs may also contain various types of additives that enhance burning characteristics, produce colored flames, or both.
Artificial firelogs made of combustible particulate materials and combustible binders are typically formed by a continuous extrusion process. In such a continuous extrusion process, the combustible particulate material, the combustible binder, and any desired additives are admixed to produce a component mixture. The component mixture is compressed within an extrusion bore with a screw extruder. The extruded stream passing through the extrusion bore is forced through an extrusion die to form the extruded component mixture into a desired size and shape. The extruded stream exiting the extrusion die is then cut to a desired length and placed into a protective wrapper.
Many artificial firelogs formed by extrusion are of a substantially cylindrical shape for the purpose of simulating a wooden log. Other firelogs contain various configurations intended to enhance the aesthetic qualities of the resultant fire, the burn characteristics of the firelogs, or the appearance of the firelog itself. The aesthetic qualities of the fire and the burn characteristics of the firelogs are among the most significant considerations in design and development of an artificial firelog.
Another consideration is the safety factors involved with burning an artificial firelog. Such safety factors relate to the stability of a partially burned firelog, the amount of heat generated by a burning firelog, and the length of time an artificial firelog will burn. The latter consideration, i.e., length of burning time, is an important safety consideration inasmuch as a burning firelog is preferably not left unattended since burning firelogs can cause dangerously high oxygen depletion and can potentially ignite the building structure. An artificial firelog thus should only burn for an appropriate period of time, remain structurally stable while burning, and not generate undue amounts of heat.
One firelog configuration that is aesthetically pleasing while being safe is the use of a pair of upstanding firelogs that have a flat rear surface and a curved front surface. A channel disposed on the rear surface helps position the firelog on a support. It is thus desired in the art to provide a method for manufacturing these logs that is inexpensive but consistently yields quality logs.
Various processes have been developed to fabricate safe artificial firelogs. For instance, U.S. Pat. No. 4,326,854 to Tanner discloses a process for making an artificial firelog in which a component mixture is compressed through an extrusion bore with the screw extruder, the screw extruder containing a cylindrical mandrel concentric with its axis of rotation whereby the rotating screw extruder and mandrel combination produce a hollow cylindrical firelog. While this process is effective for fabricating hollow logs, at least an additional step must be added to create the flat-backed logs discussed above.
While many possible configurations and processes exist for making firelogs, competition in the relevant industry mandates that artificial firelogs be produced as inexpensively as possible. It is thus desired to provide a process for manufacturing an artificial firelog having appropriate aesthetic, burning, and safety characteristics that can be inexpensively produced with existing machinery and existing assembly lines.
In view of the foregoing, an objective of the invention is to provide a process for manufacturing an artificial firelog having appropriate aesthetic, burning, and safety characteristics.
An additional objective of the invention is to provide a process for manufacturing an artificial firelog that is relatively inexpensive.
An additional objective of the invention is to provide a process for manufacturing an artificial firelog that produces a firelog having a stable support surface.
An additional objective of the invention is to provide a process for manufacturing an artificial firelog that can be used substantially in conjunction with existing machinery and production lines.
An additional objective of the invention is to provide a method for creating a pair of firelogs that each have a flat rear surface.
An additional objective of the invention is to provide a method for fabricating a pair of flat-backed firelogs wherein a support channel is formed in the flat rear surface.
An additional objective of the invention is to provide a method of fabricating artificial firelogs where two firelogs are fabricated simultaneously.
These and other objectives and advantages of the invention are obtained from the process for manufacturing artificial firelogs, the general nature of which can be stated as including the steps of moving the component mixture through an extrusion bore, dividing the component mixture, forming a rear surface on the component mixture, forming a channel on the component mixture, and cutting the component mixture to desired lengths.